Super Air Knife Provides Tension with Fine Adjustment for a Lightweight Plastic Film

A company had a small converting machine that was winding a plastic film onto a roll. The width of the plastic film was only 3” across, and the amount of tension required for a consistent roll was small. The maximum amount of tension without damaging the plastic film was 16 ounces of force.  In converting media onto rolls, it is very important to control the tension on the web to reduce defects like wrinkles, out-of-round rolls, or stretching.

They explained the setup that they were trying. They had a 4” manifold with two 2” wide “duck-foot” nozzles attached.  They sent a hand drawing to better describe what they were using. (See below).  The issue that they were seeing was too much variation in the blowing force being applied to the film.  To get near the correct blowing force, they had to start at an air pressure of about 18 PSIG.  As they ran the process, the operator would have to adjust the pressure continuously to evenly roll the film onto the core.  The process was out of control, and they wondered if EXAIR had a better way to evenly exert this force.

Dual Flat Nozzle Manifold
Dual Flat Nozzle Manifold

In analyzing the drawing and their setup, I noticed a couple of things that could cause the variations. I modified his drawing to better explain the situation (Reference below).  As compressed air leaves the two flat nozzles, the center section will overlap.  This overlap will cause turbulence in the air flow pattern.  In order to get an even distribution of forces across the width of the product, turbulence cannot exist.  Turbulence is a mixing pattern where the velocity is not linear; thus, causing high and low pressure points on the target.  The other thing that I noticed was the low air pressure that they could not go above.  This limited the precision of the incremental forces.  Because of the fixed openings of the two nozzles, they had to have a ceiling with the air pressure at 18 PSIG for 16 ounces of force.  If they had to “bump” the force level, the change was difficult to hit exactly.  If we divided the 16 ounces of force between 0 – 18 PSIG, we would get roughly 0.9 ounce of force per PSIG.  You lose the accuracy to make fine adjustments.

Overlap of air flow pattern
Overlap of air flow pattern

I recommended our model 110003, 3” Super Air Knife and a model 110303 Shim Set. The Super Air Knife blows compressed air across the entire length.  Without any overlap, the flow is laminar, and the velocity profile is moving in the same direction.  Thus, an even force across the entire 3 inches.  The Shim Set comes with additional shim thicknesses of 0.001”, 0.003”, and 0.004” thick (the standard thickness of 0.002” is installed in the Super Air Knife). In working with such a precise force requirement, they needed additional options for more control.  They could change the shims as a coarse adjustment and adjust their pressure regulator as a fine adjustment.  This combination gave them the best results to accurately dial in the correct force and not damage the material.  With the maximum requirement of 16 ounces across 3 inches of film, they were able to change the shim to the 0.004” thickness.  For the model 110003 Super Air Knife, it put them at a maximum pressure of 86 PSIG, not 18 PSIG.  Thus the increment was now 0 – 86 PSIG for 16 ounces of force, or 0.19 ounces per PSIG.  There was much more resolution to make smaller changes to the force levels thus optimizing their adjustment range.

Super Air Knife with Shim Set
Super Air Knife with Shim Set

In replacing the competitor’s product with a Super Air Knife, our customer had all the necessary control to wrap rolls of film without issue. The setup with the nozzles on a manifold design resulted in turbulence, which was noisy and produced inconsistent results.  It also restricted their adjustment resolution in changing forces, as they do not use shims.  If you would like to exert a greater degree of precision blowing with products like the Super Air Knife, please contact us. We would be happy to discuss your application and help you meet such goals.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Super Air Amplifier Keeps Web Tension Clutch Cool

SAL
Model 120022 2″ Super Air Amplifier

I was working with a new customer today who was in the maintenance department at a printing company. He called because he was looking for a cooling solution to a heat build-up problem that his company was having on one of their pneumatically controlled web tensioner systems. The heat was building up in the pneumatic clutch which was housed inside a box along-side the web roller shaft. The customer had just replaced the clutch not even one month ago and production had called them down because it was making noises again.

After performing some routine checks, maintenance determined that production was operating the line at a speed higher than what the clutch was designed for in order to meet production goals. The unfortunate part was that being inside an enclosure did not allow heat to dissipate quickly enough from the clutch itself. So, the customer wanted to know how EXAIR products might be able to help them with this heat dissipation issue.

Once I had an understanding of the application and the nature of the problem, I guided the customer to utilize model 120022 (2” Super Air Amplifier). The clutch housing became so hot that they could not touch it with bare hands. That established the fact that the temperature of the housing already had the established temperature differential that was needed. All we needed to do was to provide a flood of room temperature air into this enclosure and also direct it at the clutch’s friction surface to quickly dissipate that heat.

You might ask why the customer didn’t opt to use fans. The reason is that fans were not sufficient enough to drop the temperature of the clutch during periods of extreme operation. The clutch housing actually needed to be doused with a high velocity airflow that was non-turbulent in nature. This is precisely the kind of airflow that exits the Super Air Amplifier. Because it is laminar (non-turbulent), 100% of the air volume will be directed to impact the target surface. With fans, you do not get that and thus an overall reduction in cooling effectiveness when compared to an Air Amplifier. Also, an Air Amplifier uses only a small volume of air to induce a much larger flow of ambient air to perform the cooling task.

Many times automotive component manufacturers will use Air Amplifiers in a similar manner when they are testing shocks, struts, brakes and other suspension parts to simulate real world air movements while the components are under test in a test cell. When testing without air flowing around the component, excessive heat builds up and can cause premature wear and failure. Similar to the issue with the pneumatic clutch described above.

The Super Air Amplifiers are a great tool for providing localized cooling to carry heat away from components or other tools when they are being operated under stressful or less than ideal conditions. Think about your operations. Do you have some component that fails consistently due to overheating conditions? If so, contact us to discuss your application and see how we may be able to help.

Neal Raker, International Sales Manager
nealraker@exair.com
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